With popularity of Instant Messaging and upgrading of network bandwidth of Internet, more and more users start using a camera for video chat. However, due to limitations of bandwidth and network quality of a current Internet Protocol (IP) network, data amount of each frame of video transmitted in the IP network is limited; therefore, it is required to perform data compression coding on video images transmitted over the IP network.
In prior art, when data compression coding is performed on a video image, the data amount of each frame is distributed evenly in the entire frame image to ensure the overall image quality, while it does not concern about whether a certain area in a frame image needs more code stream to be distributed or not.
In the process of achieving the present invention, the inventors found that the above-mentioned method for video image compression coding in prior art has following disadvantages: after a compression coding is performed on a video image and the compressed video image is transmitted over an IP network, the overall image quality is inevitably declined, so that details of the image could not be seen clearly by a user of a receiving side.